Organic acid compositions for use in the oil and gas industry

ABSTRACT

An organic acid composition for use in oil industry activities, said composition comprising: methane sulphonic acid; a metal iodide or iodate; and an alcohol or derivative thereof. The uses include: injection/disposal in wells; squeezes and soaks or bullheads; acid fracturing; acid washes or matrix stimulations; fracturing spearheads (breakdowns); pipeline scale treatments; cement breakdowns or perforation cleaning; pH control; and de-scaling applications.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority benefit of Canadian Patent ApplicationSerial No. 2,892,895, filed May 28, 2015, the disclosure of which ishereby incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

This invention relates to acid compositions for use in performingvarious treatments in the oil and gas industry, more specifically toorganic acid compositions as alternatives to conventional acids.

BACKGROUND OF THE INVENTION

In the oil and gas industry, stimulation with an acid is performed on awell to increase or restore production. In many situations various sizesof casing are placed in a well to prevent water table supplycontamination, provide isolation between various formations to limitdrilling fluid losses, contain high pressure formations, provide a meansto secure down hole production equipment such as electric submersiblepumps, pressure sensing equipment and isolation production strings etc.To secure these various lengths of casing cement is utilized whichtypically is of a very high density and resistant to degradation byproduced well fluids as well as conventional acids, such as hydrochloricacid. After the well is drilled, a completion program is typicallycommenced which will stimulate the formations or zones of interest tostimulate oil and gas fluids to flow from the formation into thewellbore. During these stimulations fluids, gels, proppants, chemicalsand gases such as nitrogen will be pumped into the formation via thecasing perforations (or other completion technique).

One of the challenges facing the industry is breaking down, or cleaningthe residual cement and debris left in the perforations or breakingthrough the actual cement sheath in certain completion techniques suchas cemented sleeve ports. During a cemented sleeve port completionoperation, coiled tubing tools (or a shifting ball) will be deployedcapable of “sliding open” the sleeve which is placed and cemented inposition during the casing placement stage of the wells drilling cycle(at the end of the drilling cycle). Once these sleeves are opened thereis typically a cement sheath inhibiting flow from the casing to theformation. Acids are typically deployed prior to the frac fluid stage(this acid stage is called a “spearhead”). Most cement blends commonlyutilized in the oil and gas industry have minimal acid solubility,hindering the effectiveness of most conventional acids.

Another major challenge operators face is executing remedial (cement)work on existing wells for either the purpose of sealing a leak in thecement portion of the well (causing a communication of well fluids to anundesirable section of the formation or well face), or for anabandonment of a well whose life cycle has expired. In both of theseexamples there is usually a need to seal any leaks that may be presentby executing a “cement squeeze”. Typically an acid is pumped prior tothe new cement to be placed to ensure an unobstructed pathway for theplacement of the new cement to seal the leak or communication. In thesesituations it is sometimes difficult to obtain an acceptable injectionrate of the cement due to the inability of current acids typically usedin the industry to solubilize the cement sufficiently.

Common day to day operations utilizing organic and mineral acids in theoil and gas industry include three major types of acid applications:matrix acidizing, fracture acidizing, and spearhead breakdown acidizing.A matrix acid treatment is performed when acid is pumped into the welland into the pores of the reservoir formation below the fracturepressure. In this form of acidization, the acids dissolve the sedimentsand mud solids that are inhibiting the permeability of the rock,enlarging the natural pores of the reservoir (wormholing) andstimulating flow of hydrocarbons. While matrix acidizing is done at alow enough pressure to keep from fracturing the reservoir rock, fractureacidizing involves pumping highly pressurized acid into the well,physically fracturing the reservoir rock and etching the permeabilityinhibitive sediments. This type of acid treatment forms channels orfractures through which the hydrocarbons can flow.

There are many different mineral and organic acids used to perform anacid treatment on wells. The most common type of mineral acid employedon wells to stimulate production is hydrochloric acid (HCl), which isuseful in stimulating carbonate reservoirs.

One of the major challenges faced in the oil and gas industry from usinghydrochloric acid is the extremely high levels of corrosion (which iscountered by the addition of ‘filming’ corrosion inhibitors that aretypically themselves toxic and harmful to humans, the environment andequipment, and are very difficult to maintain in solution with the acidover a period of time); reactions between acids and various types ofmetals can vary greatly but certain metals, such as aluminum andmagnesium, are very susceptible to major effects causing immediatedamage. Also, hydrochloric acid produces hydrogen chloride gas which istoxic (potentially fatal) and corrosive to skin, eyes and metals. Atlevels above 50 ppm (parts per million), it can be Immediately Dangerousto Life and Health (IDHL). At levels from 1300-2000 ppm death can occurin 2-3 minutes. The current invention involves an acid that isnon-fuming, eliminating this risk for industry personnel.

The inherent environmental effects (organic sterility, poisoning ofwildlife etc.) of hydrochloric acids in the event of an unintended oraccidental release on surface or downhole into water aquifers or othersources of water are devastating which can cause significant pHreduction of such and can substantially increase the toxicity and couldpotentially cause a mass culling of aquatic species and potentialpoisoning of humans or livestock and wildlife exposed to/or drinking thewater. An unintended release at surface can also cause a hydrogenchloride gas cloud to be released, potentially endangering human andanimal health. This is a common event at large storage sites when tankssplit or leak. Typically if near the public, large areas need to beevacuated post event. Because of its acidic nature, hydrogen chloridegas is also corrosive, particularly in the presence of moisture.

The inability for conventional acids and blends of such to biodegradenaturally without neutralizing the soil results in expensivecleanup-reclamation costs for the operator should an unintended releaseoccur. Moreover, the toxic fumes produced by mineral and many organicacids (acetic and formic in particular) are harmful to humans/animalsand are highly corrosive and/or explosive potentially. Transportationand storage requirements for these acids are quite restrictive andtaxing in such that you must typically haul the products in specializedacid tankers or intermediate bulk containers (IBC) that are rated tohandle such corrosive products, bringing exposure dangers for personnelexposed to handling.

Another concern is the potential for spills on locations due to the highcorrosion levels of conventional acids which can cause storage containerfailures and/or deployment equipment failures i.e. coiled tubing orfracturing iron failures caused from high corrosion rates (pitting,cracks, pinholes and major failures). Other concerns include: downholeequipment corrosion causing the operator to have to execute a work-overand replace down hole pumps, tubing, cables, packers etc.; high levelsof corrosion on surface pumping equipment resulting in expensive repairand maintenance levels for operators and service companies; therequirement of specialized equipment that is purpose built to pump acidsgreatly increasing the capital expenditures of operators and servicecompanies; and the inability to source a blended product locally or verynear its end use.

Another problem for industry utilizing conventional acids, and certainacid replacements is high temperature stability. Several operations inthe oil industry expose fluids and equipment to very high temperatures(some upward of 200° C.). The compositions used in these variousoperations need to withstand these high temperatures without losingtheir effectiveness. These compositions must be capable of being used inoperations over a wide range of temperatures while not affecting theequipment with which it comes in contact and yet still remain stable.The current invention has stability up over 180 degrees Celsius and willnot lose its solubilizing characteristics as temperature increases asmany mineral acids do. Having a high temperature, chemically stable,acid is very attractive to industry for multiple functions such as, butnot limited to, acid fracturing, remedial operations, freeing stuckdrilling pipe, spearhead acids, high temperature scale mitigation, andconstant injection applications for SAGD (Steam Assisted GravityDrainage) programs.

When used to treat scaling issues on surface due to water/fluidprecipitation, acids are exposed to personnel and mechanical devices aswell as expensive pumping equipment causing increased risk for theoperator and corrosion effects that damage equipment and createhazardous fumes. Conventional acids typically need to be blended withfresh water (due to their intolerance of highly saline water, causingprecipitation of minerals) to the desired concentration requiringcompanies to pre-blend off-site as opposed to blending on-site withproduced water thereby increasing costs associated with transportation.

When using an acid to pickle tubing or pipe, very careful attention mustbe paid to the process due to high levels of corrosion, as temperaturesincrease, the typical additives used to control corrosion levels in acidsystems begin to degrade very quickly (due to the inhibitors “platingout” on the steel) causing the acids to become very corrosive andresulting in damage to equipment/wells. Having to deal with ‘live’ acidduring the back flush process is also very expensive as conventionalacids typically are still at a very low pH and toxic. It is advantageousto have an acid blend that can be exported to production facilitiesthrough pipelines that once spent or applied, is commonly a neutral pHgreatly reducing disposal costs/fees.

Typically, up to 10 chemical additives can be required to controlvarious aspects of the acids performance adding to obstacles in thehandling and shipping logistics. Having an alternative that onlyrequires minimal additives is very advantageous.

In wells that have a high degree of sour gas (hydrogen sulphide) andcarbon dioxide, in its composition, there is always a high concern ofcorrosion. Pipelines are especially of concern, as many variables cancreate unwanted corrosion and pitting attack on the steels. Any presenceof water containing hydrogen sulphide in combination with a certainamount of chlorides will create an acidic effect on the steel,potentially creating corrosion related failures. Any amount ofprotective scaling mechanism that is generated on the sour gas pipelinewalls can also be subject to scale disruption in the presence ofchlorides, exposing the surface to corrosion attack. The use of ahydrochloric acid in these types of applications is obviously notpossible, due to the high level of chlorides in the mineral acid.Utilizing a high strength acid for downhole scale removal that hasvirtually no chloride level is an obvious advantage to the application.

Acids perform many actions in the oil and gas industry and areconsidered necessary to achieve the desired production of variouspetroleum wells, maintain their respective systems and aid in certainfunctions (i.e. remedial well intervention, or abandonment of a wellthat has expired its life cycle). The associated dangers that come withusing acids are expansive and tasking to mitigate through controls,whether they are chemically or mechanically engineered. Eliminating, oreven simply reducing, the negative effects of acids while maintainingtheir usefulness is a struggle for the industry, especially at highertemperatures encountered downhole. As the public demand for the use ofcleaner/safer/greener products increases, companies are looking foralternatives that perform the required function without all, or most ofthe, drawbacks associated with the use of conventional acids.

The composition according to the present invention can ideally be usedin various oilfield operations; spearhead acid, fracking operations,injection/disposal well injectivity treatments, scale treatments(surface and subsurface-wells equipment, pipelines, facilities), filtercake removal, tubing pickling, bullhead/annular squeezes and soaks,cement squeezes, fluids pH control, stuck pipe treatment.

Therefore, the present invention answers the need for both a simplermanufacturing process and abridged, novel organic acid compositions foruse in high volume operations in oilfields throughout the world.

Consequently, there is still a need for compositions for use in the oilindustry which can be used over a range of applications which candecrease a number of the associated dangers/issues typically associatedwith acid applications to the extent that these acid compositions areconsidered much safer for handling on worksites, stable at a range oftemperatures, and which are chloride-free.

SUMMARY OF THE INVENTION

Compositions according to the present invention have been developed forthe oil and gas industry and its associated applications by specificallytargeting the problems of corrosion, logistics-handling,human-environmental exposure, formation fluid compatibilities, flow-backfluid compatibilities, biodegradability, chloride content and hightemperature stability.

It is an object of the present invention to provide a novel organic acidcomposition which can be used over a broad range of applications in theoil and gas industry and which will exhibit advantageous properties overknown compositions, but more specifically for operations requiring ahigh solubilizing effect on various high strength cements utilized inthe oil and gas industry down hole. According to a preferred embodimentof the present invention, the novel organic acid composition should beable to highly solubilize various types of downhole scales, without anypresence of chloride ions in the acid composition.

According to one aspect of the present invention, there is provided anovel organic acid composition which, upon proper use, results in a verylow corrosion rate of oil and gas industry activities equipment on mostall types of metals

According to another aspect of the present invention, there is provideda novel organic acid composition for use in the oil industry which isreadily biodegradable.

According to another aspect of the present invention, there is provideda novel organic acid composition for use in the oil industry which isnon-fuming, non-toxic, and has a highly controlled manufacturing processensuring consistent end product strength.

According to another aspect of the present invention, there is provideda novel organic acid composition for use in the oil industry which has apH below 1. Preferred compositions according to the present inventioncan be utilized in common day to day operations utilizing organic andmineral acids in the oil and gas industry which operations are selectedfrom the group consisting of: matrix acidizing, fracture acidizing, andspearhead breakdown acidizing.

According to another aspect of the present invention, there is provideda novel organic acid composition that is stable at very hightemperatures (>180° C.).

According to a preferred embodiment of the present invention, there isprovided a novel organic acid composition for use in the oil industrywhich has high salinity tolerance. A tolerance for high salinity fluids,or brines, is desirable for onshore and offshore acid applications.Typical acids are blended with fresh water and additives, typically faroffsite, and then transported to the area of treatment as a finishedblend. It is advantageous to have an alternative that can be transportedas a concentrate safely to the treatment area, then blended with a highsalinity produced water or sea water greatly reducing the logisticsrequirement typical with conventional acid systems. A typical acidsystem could precipitate salts/minerals heavily if blended with fluidsof an excessive salinity level resulting in formation plugging orancillary damage inhibiting production and substantially increasingcosts. Brines are also typically present in formations, thus having anacid system that has a high tolerance for brines greatly reduces thepotential for formation damage or emulsions down-hole during or afterproduct placement/application.

According to another aspect of the present invention, there is provideda novel organic acid composition for use in the oil industry which isimmediately reactive upon contact/application.

According to another aspect of the present invention, there is provideda novel organic acid composition that has a high solubilizing effect onhigh strength cements commonly utilized down hole in the oil and gasindustry.

Most cement blends commonly utilized in the oil and gas industry haveminimal acid solubility, hindering the effectiveness of mostconventional acids. Preferred embodiments of the present invention willreadily solubilize these cement blends, which effectively save theoperator substantial time and potentially reducing the volumes requiredto achieve a clean path from the wellbore to the formation/zone ofinterest.

According to another aspect of the present invention, there is provideda novel organic acid composition that has a high solubilizing effect onvarious downhole scales without any chloride ions present in thecomposition.

Accordingly, the product would overcome many of the drawbacks found inthe use of compositions of the prior art related to the oil and gasindustry.

According to an aspect of the present invention, there is provided anorganic acid composition for use in oil industry activities, saidcomposition comprising: methanesulphonic acid; a metal iodide or iodate;and an alcohol or derivative thereof.

According to a preferred embodiment of the present invention, the metaliodide or iodate is cuprous iodide. According to another preferredembodiment, the metal iodide or iodate is potassium iodide. According toanother preferred embodiment, the metal iodide or iodate is sodiumiodide. According to yet another preferred embodiment, the metal iodideor iodate is lithium iodide.

According to a preferred embodiment of the present invention, thealcohol or derivative thereof is an alkynyl alcohol or derivativethereof. Preferably, the alkynyl alcohol or derivative thereof ispropargyl alcohol or a derivative thereof. Preferably, the alkynylalcohol or derivative thereof is present in a concentration ranging from0.05 to 2.0% w/w, preferably from 0.05 to 1.0% w/w. More preferably, thealkynyl alcohol or derivative thereof is present in a concentration of0.25% w/w.

According to a preferred embodiment of the present invention, the metaliodide is present in a concentration ranging from 100 to 10000 ppm, morepreferably from 100 to 5000 ppm. Preferably, the metal iodide is presentin a concentration of 1000 ppm.

According to a preferred embodiment of the present invention, there isprovided an organic acid composition for use in oil industry activities,said composition comprising:

-   -   water present in an amount ranging from 30 to 80% by weight of        the weight of the composition;    -   methanesulphonic acid present in an amount ranging from 30 to        70% by weight of the weight of the composition;    -   a metal iodide or iodate present in an amount of no more than 1%        by weight of the weight of the composition; and    -   an alcohol or derivative thereof present in an amount of no more        than 2% by weight of the weight of the composition.

According to a preferred embodiment of the present invention, the majorsolvent of the composition is water which thus makes the composition anenvironmentally friendly composition for use in oil industry operations.

According to a preferred embodiment of the present invention, thecomposition uses water used as solvent which allows for increasedsolubilising of CaCO₃ which thus makes the composition both anenvironmentally friendly composition and effective in various oilindustry operations.

According to an aspect of the present invention, there is provided a useof an organic acid composition in the oil industry to stimulateformations.

According to an aspect of the present invention, there is provided a useof an organic acid composition in the oil industry to assist in reducingbreakdown pressures during downhole pumping operations.

According to an aspect of the present invention, there is provided a useof an organic acid composition in the oil industry to treat wellborefilter cake post drilling operations.

According to an aspect of the present invention, there is provided a useof an organic acid in the oil industry to assist in freeing stuck pipe.

According to an aspect of the present invention, there is provided a useof an organic acid composition in the oil industry to descale pipelinesand/or production wells.

According to an aspect of the present invention, there is provided a useof an organic acid composition in the oil industry to increaseinjectivity of injection wells.

According to an aspect of the present invention, there is provided a useof an organic acid composition in the oil industry to lower the pH offluids.

According to an aspect of the present invention, there is provided a useof an organic acid composition in the oil industry to remove undesirablescale in surface equipment, wells and related equipment and/orfacilities.

According to an aspect of the present invention, there is provided a useof an organic acid composition in the oil industry to fracture wells.

According to an aspect of the present invention, there is provided a useof an organic acid composition in the oil industry to complete matrixstimulations.

According to an aspect of the present invention, there is provided a useof an organic acid composition in the oil industry to conduct annularand bullhead squeezes and soaks.

According to an aspect of the present invention, there is provided a useof an organic acid composition in the oil industry to pickle tubing,pipe and/or coiled tubing.

According to an aspect of the present invention, there is provided a useof an organic acid composition in the oil industry to increase effectivepermeability of formations.

According to an aspect of the present invention, there is provided a useof an organic acid composition in the oil industry to reduce or removewellbore damage.

According to an aspect of the present invention, there is provided a useof an organic acid composition in the oil industry to cleanperforations.

According to an aspect of the present invention, there is provided a useof an organic acid composition in the oil industry to solubilizelimestone, dolomite, calcite and combinations thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It will be appreciated that, numerous specific details have provided fora thorough understanding of the exemplary embodiments described herein.However, it will be understood by those of ordinary skill in the artthat the embodiments described herein may be practiced without thesespecific details. In other instances, well-known methods, procedures andcomponents have not been described in detail so as not to obscure theembodiments described herein. Furthermore, this description is not to beconsidered so that it may limit the scope of the embodiments describedherein in any way, but rather as merely describing the implementation ofthe various embodiments described herein.

The description that follows, and the embodiments described therein, areprovided by way of illustration of an example, or examples, ofparticular embodiments of the principles of the present invention. Theseexamples are provided for the purposes of explanation, and notlimitation, of those principles and of the invention.

According to an aspect of the invention, there is provided a novelorganic acid composition comprising: methanesulphonic acid; a metaliodide or iodates, preferably cupric iodide, potassium iodide, lithiumiodide or sodium iodide; and an alcohol or derivatives thereof,preferably alkynyl alcohol or derivatives thereof, more preferably2-Propyn-1-ol (or a derivative of) complexed with methyloxirane.

Alcohols and derivatives thereof, such as alkyne alcohols andderivatives and more preferably 2-Propyn-1-ol complexed withmethyloxirane can be used as corrosion inhibitors. Propargyl alcoholitself is traditionally used as a corrosion inhibitor which worksextremely well at low concentrations. It is however a verytoxic/flammable chemical to handle as a concentrate, so care must betaken while handling the concentrate. In the composition according tothe present invention, 2-Propyn-1-ol complexed with methyloxirane isutilized where the toxic effect does not negatively impact the safety ofthe composition. There are derivatives of propargyl alcohol available inthe industry now that are considered safe to handle, non-regulated, andapproved for use in North Sea Offshore Oilfield applications. This isthe preferred chemistry for the present composition.

Metal iodides or iodates such as potassium iodide, sodium iodide,cuprous iodide and lithium iodide can potentially be used as corrosioninhibitor intensifier. In fact, potassium iodide is a metal iodidetraditionally used as corrosion inhibitor intensifier, however it isexpensive, but works extremely well. It is non-regulated, friendly tohandle, and listed on the offshore PLONOR (Pose Little Or NO Risk) listas safe chemicals to the environment.

Example 1 Formulation and Process to Prepare a Composition According toa Preferred Embodiment of the Invention

Start by combining the methanesulphonic acid with the water and mixthoroughly for a few minutes. Add 2-Propyn-1-ol, complexed withmethyloxirane, and potassium iodide. Circulation is maintained until allproducts have been solubilized. Table 1 lists the components of thecomposition of Example 1, including their weight percentage as comparedto the total weight of the composition and the CAS numbers of eachcomponent.

TABLE 1 Composition of a preferred embodiment of the present invention %Wt Chemical Composition CAS# Water 57.65% 7732-18-5 Methane SulphonicAcid   42% 75-75-2 2-Propyn-1-ol, complexed  0.25% 38172-91-7 withmethyloxirane Potassium Iodide  0.1% 7681-11-0

The resulting composition of Example 1 is a clear, odourless liquidhaving shelf-life of greater than 1 year. It has a freezing pointtemperature of approximately minus 30° C. and a boiling pointtemperature of approximately 100° C. It has a specific gravity of1.21±0.02. It is completely soluble in water and its pH is less than 1.

The composition is readily biodegradable, non-fuming and has no volatileorganic compounds nor does it have any BTEX levels above the drinkingwater quality levels. BTEX refers to the chemicals benzene, toluene,ethylbenzene and xylene. Surrogate toxicity testing carried out on ratsshows the LD50 to be not less than 1100 mg/kg.

With respect to the corrosion impact of the composition on typicaloilfield grade steel, it was established that it was clearly well belowthe acceptable corrosion limits set by industry for certainapplications, such as spearhead applications or downhole scaling.

In preferred embodiments of the present invention 2-Propyn-1-olcomplexed with methyloxirane can be present in a range of 0.05-2.0%,preferably 0.05 to 1%, more preferably it is present in an amount ofapproximately 0.25%. Potassium Iodide can be present in a range of0.01-1.0%, more preferably from 0.01-0.5%. According to certainpreferred embodiments, it is preferably it is present in an amount ofapproximately 0.1%.

As a substitute for 2-Propyn-1-ol complexed with methyloxirane one coulduse propargyl alcohol, however, 2-Propyn-1-ol complexed withmethyloxirane is preferable. As a substitute for potassium iodide onecould use sodium iodide, copper iodide and lithium iodide. However,potassium iodide is the most preferred.

Corrosion Testing

The compositions according to the present invention were exposed tocorrosion testing. Samples of N80 grade steel were exposed to variousnovel organic acid solutions for periods of time ranging up to 24 hoursat 90° C. temperatures.

TABLE 2 Corrosion testing using the composition of Example 1 InitialFinal Loss Surface Run Coupon - wt. wt. wt. area Density time Mils/ Mm/Lb/ Concentration (g) (g) (g) (cm2) (g/cc) (hours) yr year ft2 N80 -100% of 40.469 40.429 0.040 27.11 7.86 6 107.901 2.741 0.003 theformulation of Ex. 1 N80 - 100% of 40.469 40.404 0.065 27.11 7.86 2443.834 1.113 0.005 the formulation of Ex. 1 N80 - 33% of 40.774 40.5090.265 27.11 7.86 6 714.845 18.157 0.019 the formulation of Ex. 1 N80 -33% of 40.774 39.776 0.998 27.11 7.86 24 673.033 17.095 0.072 theformulation of Ex. 1

This type of corrosion testing helps to determine the impact of the useof such novel organic replacement acid composition according to thepresent invention compared to the industry standard (HCl alone or anyother mineral or organic acid). Additionally, the compositions accordingto the present invention will allow the end user to utilize analternative to conventional acids that has the down-hole performanceadvantages, transportation and storage advantages as well as the health,safety and environmental advantages for a nominal cost difference.Improvement in corrosion control is one of the distinct advantages ofthe present invention. The high salt tolerance is another advantage ofcomposition according to the present invention.

Aquatic Toxicity Testing

The biological test method that was employed was the Reference Methodfor Determining acute lethality using rainbow trout (1990—EnvironmentCanada, EPS 1/RM/9—with the May 1996 and May 2007 amendments).

The formulation tested was the following: 42% MSA+0.5% Basocorr+500 ppmKI+0.2% surfactant. Basocorr® is a tradename for a corrosion inhibitorfrom BASF.

The Trout 96 hour Acute Test (WTR-ME-041) was performed at 5 differentconcentrations of compositions (62.5, 125, 250, 500 and 1000 ppm) onereplicate per treatment, ten fish per replicate.

The test results indicate that at concentrations of the formulationtested of up to and including 500 ppm there was a 100% survival rate inthe fish sample studied. This is an indicator that the formulationtested demonstrates a very acceptable environmental safety profile.

Oral Toxicity

The composition of Example 1 was tested on rats to assess the oraltoxicity. It was determined to be as follows: LD50 (Rat) 650 mg/kg

Environmental Testing

The biodegradability of formulation of Example 1 was tested followingthe OECD 301A (new version) test.

The dissolved organic carbon (DOC) reduction—>70% (product is readilybiodegradable), thus confirming that the formulation tested wasbiodegradable.

Marble Dissolution Testing

The potential to dissolve marble was tested using several strength oftwo blends according to preferred embodiments of the present invention.This test helps to assess the extent and reactivity of formulationsaccording to the present invention with respect to downhole operations.

The test involved exposing 25 ml of acid with excess of marble chips at20° C. As a control, 25 ml of 42% MSA will dissolve 7.2 g of marble andevolve 3.268 g of CO₂.

Formulation A:  42% MSA Formulation B:  35% MSA 0.2% Basocorr ® 0.5%Basocorr ® 200 ppm KI 500 ppm KI 0.2% surfactant

TABLE 3 Weight loss (in grams) vs Time of Exposure (in minutes) Time(minutes) Composition 0 0.5 1 5 10 20 40 60 80 120 200 Formulation A 00.002 0.003 0.009 0.016 0.036 0.089 0.141 0.188 0.283 0.454 at 100%blend Formulation A 0 0.016 0.036 0.24 0.469 0.75 1.035 1.16 1.23 1.3121.412 at 50% blend Formulation A 0 0.01 0.018 0.117 0.235 0.421 0.640.744 0.804 0.878 0.958 at 33% blend Formulation B 0 0.005 0.016 0.1460.303 0.546 0.836 1.024 1.134 1.234 1.304 at 50% Formulation B 0 0.0050.013 0.131 0.272 0.476 0.665 0.734 0.77 0.809 0.84 at 33% ForFormulation A at 50% blend, at 100% spent the evolution of CO₂ was of1.634 grams. For Formulation A at 33% blend, at 100% spent the evolutionof CO₂ was of 1.08 grams.

Example 2

A composition according to a preferred embodiment of the presentinvention was prepared similarly to Example 1 with the followingcomponents:

TABLE 4 Composition of Example 2 Chemical % Wt of the Composition Water56.9%  Methane Sulphonic Acid  42% 2-Propyn-1-ol, complexed 1.0% withmethyloxirane Potassium Iodide 0.1%Corrosion Testing at Various Temperatures

Various compositions according to the present invention were tested forcorrosion inhibition at various temperatures on N80 steel for anexposure period of 6 hours. Various levels of additives were used aswell. The density of N80 steel was 7.86 g/cc and the surface area of thecoupons was of 28.0774 cm². In the examples with an additionalinhibitor, the inhibitors were added to the composition of Example 2.Table 5 lists the results of these corrosion tests.

TABLE 5 Corrosion Tests on N80 Steel Initial Final Loss Additional Tempwt. wt. wt. Mils/ Mm/ Lb/ Composition Additives (° C.) (g) (g) (g) yryear ft2 Example 2 0.01% KI 90 49.9458 48.0432 1.903 4955.487 125.8690.139 0.25% PP Example 2 0.01% KI 90 49.5539 45.8917 3.662 9538.518242.278 0.267 (diluted 50%) 0.25% PP Example 2 0.1% KI 90 50.133950.1239 0.010 26.04587 0.662 0.001 1% PP Example 2 0.1% KI 90 49.72949.156 0.573 1492.428 37.908 0.042 (diluted 50%) 1% PP Example 2 0.2% KI150 49.728 45.0934 4.635 12071.22 306.609 0.338 (diluted 50%) 2% PPExample 2 0.2% KI 90 49.735 49.7185 0.017 42.97568 1.092 0.001 (diluted50%) 2% PP Example 2 0.5% KI 150 50.4625 47.2427 3.220 8386.249 213.0110.228 (diluted 50%) 5% PP PP signifies propyn-1-ol with methyloxirane KIsignifies Potassium IodideCorrosion Testing on J55 Steel

Various compositions according to the present invention were tested forcorrosion inhibition at various temperatures on J55 steel for anexposure period of 6 hours. Various levels of additives were used aswell. The density of J55 steel was 7.86 g/cc and the surface area of thecoupons was of 28.922 cm². In the example with an additional inhibitor,the inhibitor was simply added to the composition of Example 2. Table 6lists the results of these corrosion tests.

TABLE 6 Corrosion Tests on J55 Steel at 70° C. Initial Final LossAdditional wt. wt. wt. Mils/ Mm/ Lb/ Composition Additives (g) (g) (g)yr year ft2 Example 2 0.3% PP 35.0398 30.749 4.291 10849.4 275.575 0.304Example 2 None 35.6715 35.6591 0.012 31.35372 0.796 0.001 Example 2 None33.8271 33.7974 0.030 75.09722 1.907 0.002 (50% diluted) PP signifiespropyn-1-ol complexed with methyloxirane KI signifies Potassium IodideSolubility Testing

Various compositions according to the present invention were tested fordissolving ability. Its solubilising power (in kg per m³) was assessedby exposing 50 ml of the compositions to chunks of calcium carbonate ata temperature of 23° C. for a period of up to 225 minutes. The resultsof the solubilising tests are reported in Table 7 below.

TABLE 7 Results of Solubilising Tests of CaCO₃ Chunks Total InitialFinal Weight Solubility Composition Weight/g Weight/g Loss/g kg per m³M5 15.0406 10.65 4.3906 88 Example 2 20.0055 5.7827 14.2228 284 Example19.9902 11.6328 8.3574 167 (diluted 50%) M5: commercializedMSA-containing composition

Elastomer Testing

When common sealing elements used in the oil and gas industry come incontact with acid compositions they tend to degrade or at least showsign of damage. A number of sealing elements common to the industry wereexposed to a composition according to a preferred embodiment of thepresent invention to evaluate the impact of the latter on theirintegrity. More specifically, the hardening and drying and the loss ofmechanical integrity of sealing elements can have substantialconsequences to the operations of wells and result in undesirable shutdowns to replace defective sealing elements. Testing was carried out toassess the impact of the exposure of composition of Example 2 to variouselastomers. Table 8 relates the results of the long term (72 hourexposure) elastomer testing on the concentrated product of Example 2 at70° C. and 28,000 kPa showed little to no degradation of variouselastomers, including Nitrile 70®, Viton 75®, Aflas 80®, and EPDM 70style sealing elements.

TABLE 8 Results of the Elastomer Testing Weight Weight Weight ThicknessThickness Elastomer before/g after/g Change/g before/g after/gNitrile ®70 2.0815 2.1381 −0.0566 0.135 0.135 AFLAS ®80 2.9354 2.9402−0.0048 0.135 0.135 VITON ®75D 3.0794 3.0855 −0.0061 0.135 0.135 EPDM70D 1.6706 1.6849 −0.0143 0.135 0.135Properties

The formulation of Example 2 was analyzed and various physical andchemical properties of the undiluted and diluted composition wererecorded in Table 9.

TABLE 9 Various Physical and Chemical Properties of the Formulation ofExample 1 at Full Strength and Upon Dilution by Half. Example 2 Example2 composition composition 50% undiluted dilution Appearance Yellowliquid Yellow liquid Specific Gravity at 23 C. 1.224 1.12 Salinity, %32% 16% Odor Slight Slight Freezing Point  −30° C.  −25° C. BoilingPoint >100° C. >100° C. pH −0.3 −0.1Corrosion Testing on Aluminum

Corrosion testing was carried out on aluminum coupons (density of 2.73g/cc) at 55° C. for a period of 72 hours. The composition of Example 2provided a substantial corrosion resistance improvement over a 15%composition of HCl and comparable corrosion resistance tomethanesulfonic acid. The surface area of the coupons was 31.53 cm². Theresults are reported in Table 10. The aluminum corrosion was below therequired minimum of 6.25 mm/year.

TABLE 10 Results of the Aluminum Corrosion test Initial Final Lossweight weight weight Mils/ Mm/ Lb/ (g) (g) (g) yr year ft2 MSA (70%)6.2763 6.2582 0.018 10.07231 0.256 0.001 Example 2 6.3235 6.2476 0.07642.23691 1.073 0.005 15% HCl 6.3114 0 6.311 3512.175 89.209 0.410 PPsignifies propyn-1-ol complexed with methyloxirane KI signifiesPotassium IodideCorrosion Testing on Chrome Coupons

Corrosion testing was carried out on Chrome 13 coupons at 55° C. for aperiod of 72 hours. The composition of Example 2 provided an improvementin the corrosion resistance versus both the MSA and the 15% HClcompositions. The coupons had a surface area of 30.88 cm², and a densityof 7.72 g/cc. The results of the test are reported in Table 11.

TABLE 11 Results of the Corrosion test on Chrome Coupons Initial FinalLoss weight weight weight Mils/ Mm/ Lb/ composition (g) (g) (g) yr yearft2 MSA (70%) 34.5027 33.9685 0.534 107.3362 2.726 0.035 Example 234.6241 34.4707 0.153 30.8225 0.783 0.010 15% HCl 34.2636 22.7195 11.5442319.543 58.916 0.767 PP signifies propyn-1-ol complexed withmethyloxirane KI signifies Potassium IodideCorrosion Testing on Chromed Stainless Steel Coupons

Corrosion testing was carried out on stainless steel coupons having achromed surface at 55° C. for a period of 72 hours. The composition ofExample 2 provided an improvement in the corrosion resistance versusboth the MSA and the 15% HCl compositions. The surface area of thecoupons was 33.22 cm², the density of the coupons was 7.86 g/cc. Theresults are reported in Table 12.

TABLE 12 Corrosion Test Results on Chromed Stainless Steel CouponsInitial Final Loss weight weight weight Mils/ Mm/ Lb/ (g) (g) (g) yryear ft2 MSA 32.11 31.4169 0.693 127.1484 3.230 0.043 Example 2 32.2432.1923 0.048 8.750507 0.222 0.003 15% HCl 32.1035 29.0324 3.071563.3896 14.310 0.189 PP signifies propyn-1-ol complexed withmethyloxirane KI signifies Potassium IodideFilter Cake Test

A filter cake was formed on a ceramic disc by heating the drilling mud(whose composition is set out in Table 15) to 50° C. with an appliedpressure of 500 psi using 12 micron aloxite disc to build 2 filtercakes. A substantial filter cake was formed. The drilling fluid wassubsequently removed from the cell and replaced with the breaker fluid.

4 Kg/m³ of Can-Break ECA was used as control filter cake breaker and thecomposition of Example 1 was used as the composition according to apreferred embodiment of the present invention. After 16 hours ofexposure, the breaker fluid was removed and the cell was dismantled toshow the filter cake on the ceramic disc. Upon visual observation, thecomposition according to the present invention had removed a significantamount of the filter cake while the standard mud enzyme breaker barelyhad any impact.

TABLE 13 Composition of Mud System used in the Filter Cake TestComponents of mud system Unit Amount Bentonite Kg/m³ 30 PACR Kg/m³ 2Starch Kg/m³ 4 Desco CF Kg/m³ 0.25 Cal Carb 325 Kg/m³ 20 Drilled solids% 3 Adjusted to pH 10 with caustic soda

Table 14 summarizes the various uses (or applications) of thecompositions according to the present invention upon dilution thereofranging from approximately 1 to 75% dilution, include, but are notlimited to: injection/disposal in wells; squeezes and soaks orbullheads; acid fracturing, acid washes or matrix stimulations;fracturing spearheads (breakdowns); pipeline scale treatments; cementbreakdowns or perforation cleaning; pH control; and de-scalingapplications.

TABLE 14 Various applications and suggested dilutions for compositionsaccording to preferred embodiment of the present invention ApplicationSuggested Dilution Benefits Injection/Disposal 50% Compatible withmutual solvents and solvent Wells blends, very cost effective. Squeezes& Soaks 33%-50% Ease of storage and handling, cost effective Bullheadcompared to conventional acid stimulations Annular Ability to leave pumpequipment in wellbore. Acid Fracs 50%-66% Decreased shipping and storagecompared to conventional acid, no blend separation issues, comprehensivespend rate encourages deeper formation penetration. Frac Spearheads33%-66% Able to adjust concentrations on the fly. (Break-downs)Decreased shipping and storage on location. Cement Break-downs 50%Higher concentrations recommended due to lower temperatures, and reducedsolubility of aged cement. pH Control 0.1%-1.0% Used in a variety ofapplications to adjust pH level of water based systems Liner De-Scaling,1%-5% Continuous injection/de-scaling of slotted Heavy Oil liners,typically at very high temperatures.

While the foregoing invention has been described in some detail forpurposes of clarity and understanding, it will be appreciated by thoseskilled in the relevant arts, once they have been made familiar withthis disclosure that various changes in form and detail can be madewithout departing from the true scope of the invention in the appendedclaims.

The invention claimed is:
 1. An organic acid composition for use in oilindustry activities, said composition comprising: water in an amountranging from 30 to 80% by weight of the weight of the composition;methanesulphonic acid in an amount ranging from 30 to 70% by weight ofthe weight of the composition; a metal iodide or iodate in an amount ofno more than 1% by weight of the weight of the composition; and analcohol or derivative thereof in an amount of no more than 2% by weightof the weight of the composition, wherein the organic acid compositionhas a pH less than 1.0 and a shelf life of greater than 12 months. 2.The organic acid composition according to claim 1, wherein the metaliodide or iodate is selected from the group consisting of: cuprousiodide; potassium iodide; sodium iodide and lithium iodide.
 3. Theorganic acid composition according to claim 1, wherein the metal iodideor iodate is potassium iodide.
 4. The organic acid composition accordingto claim 1, wherein the alcohol or derivative thereof is an alkynylalcohol or derivative thereof.
 5. The organic acid composition accordingto claim 4, wherein the alkynyl alcohol or derivative thereof ispropargyl alcohol or a derivative thereof.
 6. The organic acidcomposition according to claim 4, wherein the alkynyl alcohol orderivative thereof is present in a concentration ranging from 0.05 to2.0% w/w.
 7. The organic acid composition according to claim 4, whereinthe alkynyl alcohol or derivative thereof is present in a concentrationranging from 0.05 to 1.0% w/w.
 8. The organic acid composition accordingto claim 4, wherein the alkynyl alcohol or derivative thereof is presentin a concentration of 0.25% w/w.
 9. The organic acid compositionaccording to claim 1, wherein the metal iodide is present in aconcentration ranging from 100 to 10000 ppm.
 10. The organic acidcomposition according to claim 1, wherein the metal iodide is present ina concentration ranging from 100 to 5000 ppm.
 11. The organic acidcomposition according to claim 1, wherein the metal iodide is present ina concentration of 1000 ppm.
 12. An organic acid composition for use inoil industry activities according to claim 1, wherein themethanesulphonic acid is present in an amount ranging from 42 to 70% byweight of the weight of the composition.
 13. An organic acid compositionfor use in oil industry activities according to claim 1, wherein themethanesulphonic acid is present in an amount ranging from 51 to 70% byweight of the weight of the composition.
 14. An organic acid compositionfor use in oil industry activities, said composition comprising: waterpresent in an amount ranging from 30 to 80% by weight of the weight ofthe composition; methanesulphonic acid present in an amount ranging from30 to 70% by weight of the weight of the composition; potassium iodidepresent in an amount of no more than 1% by weight of the weight of thecomposition; and propargyl alcohol present in an amount of no more than2% by weight of the weight of the composition.
 15. An organic acidcomposition for use in oil industry activities according to claim 14,wherein the methanesulphonic acid is present in an amount ranging from42 to 70% by weight of the weight of the composition.
 16. An organicacid composition for use in oil industry activities according to claim14, wherein the methanesulphonic acid is present in an amount rangingfrom 51 to 70% by weight of the weight of the composition.